Electric controlling system



Jan. 18, 1949.

F. B. AUBERT ELECTRIC CONTROLLING SYSTEM Filed June 19, 1946 INVENTOR. 3M 6 W M M M ATTORNEY Patented Jan. 18, 1949 UNITED STATES PATENT OFFICE 2 Claims.

This invention relates to new and useful improvements in electric controlling systems and more particularly to such a system in which an electron tube is controlled by a photocell.

An object of this invention is to provide a systors in which less energy is required on the photo cell than has heretofore been necessary to render the cell conductive so that the operating life of the cell is materially increased.

Another object is to provide a system having an electron tube controlled relay which is highly sensitive to photocell operation.

The invention consists in the cooperative arrangement of parts to be more fully described hereinafter and the novelty of which will be particularly pointed out and distinctly claimed.

In the accompanying drawings, to be taken as a part of this specification, there are full and clearly illustrated several preferred embodiments of the invention, in which drawings,

Figure l is a wiring diagram showing one form of the controlling system, and

Fig. 2 is a wiring diagram showing another arrangement of the controlling system embody ing the invention.

Referring to the drawings, Fig. l, by characters of reference, the numeral 1 designates an electron tube, preferably of the gas filled type such as an R. C. A. #2051, having an anode 2, a cathode 3 of the filament heated type, a heater or filament 4, a control-grid or electrode 5 and a screen grid 6. A source of current supply, such as a 110 v. alternating current circuit having conductors or lead wires 1, 8, the wire I being the hot line and the wire 8 bieng the ground line, are connected respectively to the anode 2 and cathode 3. Across the anode-cathode circuit, there is a step-down transformer 9 having its primary I!) connected by conductors H, l2 to the wires 1, 8 respectively. The transformer has a secondary 13 preferably of say 24 v. and another secondary l4 preferably of 6 v. The cathode 3 is connected to the ground wire 8 by conductors l5, I6, I! and 18. The anode 2 is connected to the hot wire 1 by conductors I9, and 2|. In the wire or conductor l9, there is a resistor 22 for a purpose to be described. The wires 20, 2| connect to the opposite ends of a relay coil 23 of a relay switch 24 forming the load in the anode-cathode circuit and having an armature 25 cooperable with a fixed contact '26 to control an external circuit 21, 28 for a burner motor, an electric valve, or the like. Connected to the ground connected Wire l8, there is a Wire 29 which is connected to one side of a fixed condenser 30 having its other side connected by wire 3] to the anode circuit wire 29. The resistor 22 and the condenser 39 cooperate to eliminate feedback of a note into the line or supply circuit. The screen grid 53 is connected to ground by a wire 32 having in series therein a resistor 33 to determine the negative bias of the screen grid 6 and connected by wire Hi to a wire 34 connected to ground. The filament 4 is connected to the transformer secondary M by wires 35, 36, the Wire 35 being connected to the ground wire 34 by a wire 3?. The transformer secondary 53 has one end isolated from ground by a fixed condenser 38, of say 0.1 MP capacity, connected in a conductor 39 connecting from the secondar l3 to the ground wire 37. The other terminal of the secondary is connected by a conductor 46 to one side or" a variable condenser 41, of say 50 MMF capacity, having its other side connected by conductors 42, 43 to the control grid 5. The connection of the secondary I 3 to the grid 5 is such that the current to the grid 5 is reversed relative to the current to the plate or anode 2 and is 180 out of phase with respect thereto. The variable condenser 6! further shifts the current flow so that the maximum negative potential on the grid 5 leads the maximum potential on the plate 2 by about with the result that less negative swing or less negative potential on the grid 5 is required to block current flow through the tube l. The grid conductor 43 is connected by a conductor 44 to the cathode 45 of a photocell 4% having its anode 41 connected to ground by a conductor 18. The cathode 45 is positioned for impingement of light rays thereon from any light source 49 which is to control the operation of the relay switch 24, such for example as a burner flame. In series in the conductor 44 there is a resistor 56, preferably of 5 megohms, which is positioned closely adjacent the tube l and serves to prevent capacitance in the circuit to the photocell 66 from rendering the grid '5 sufficiently less negative such as will cause the t be i to become conductive or fire.

The operation of the system of Fig. l is as follows: When the line wires l and 8 are energized by an alternating current and there is no light or insuflicient light from the source 4Q on the photocell cathode 45, the grid 5 blocks current flow through the tube 1 and the relay coil 23. As noted above, the maximum negative potential on the grid 5 precedes the maximum potential on the plate 2 and as a result the tube is blocked.

by a decreasing negative potential, i. e. a poten more positive as the potential across tial becoming the anode-cathode increases. Accordingly, the tube I is extremely senitive and substantially balanced against current flow on each current surge of positive potential on the plate 2. As soon as sufiicient light from the source 49 strikes the cell cathode 45 for a negative potential drain, the grid 5 is rendered suificiently more positive or less negative such that the tube I will fire and permit current flow through the coil 23 sufficient to operate the armature 25 and close the relay switch.

Referring to Fig. 2, the electron tube Bil has a plate or anode 5|, a cathode 62, a control electrode or grid 53, a screen grid 54, and a filament or heater 55 for the cathode 62. The anode Si is connected to the hot side or conductor 55 of a 110 volt AC source having a ground wire or conductor El. From the anode 6|, a Wire 68 having a resistor 69 in series therein is connected to a Wire ll! connected to one terminal of a load or relay coil l! having its other terminal connected by a wire 12 to the line Wire or conductor 65. The coil ll of the relay switch '33 actuates an armature "E 3 cooperable with a fixed contact iii to control an external circuit having conductors i6, ll forming part of the circuit of a burner motor (not shown), or the like. The cathode 62 is connected to the ground line or wire 67 by the wires '58 and '59. The screen grid 6% is also connected to the ground wire t? by the wires 80, BI and it]. The resistor 59 cooperates with a fixed condenser 82 having one side connected by wire 83 to the plate lead or wire 58 and having its other side connected to the ground wire '6? via wires 8d, 85, Si and 19 in order to prevent feedback to the main line. Across the main line wires 55, El there is a step-down transformer 86 having its primary 8! connected by wires 83, 89 so as to be in parallel with the anode-cathode air-- edit. The transformer has a filament secondary 90, preferably 6 v., which is connected by wires 91, 92 to the filament 55. The wire 9| is grounded by a wire 93. Another secondary coil 94, preferably of 24 v., is isolated at one terminal from ground by a fixed condenser 95, of say 0.1 mi capacity, which is connected in a Wire 96 leadin from the transformer secondary 94 to the lead wire 5!. The other terminal of the secondary 94 is connected by a lead wire 91 to one side of a variable condenser 98, preferably of 50 m. m. i. capacity, having its other side connected to the control grid 63 by wires 99, iii. Connected to the grid lead E0!) is the cathode lili of a photocell H12 which is energized from a light source )3 which may be a fuel burner or other dominating device for the relay switch '13. The conductor 194 which connects the cell cathode iii! to the grid lead I90 contains a resistor Hi5, preferably of 5 megohms, positioned closely adjacent the tube ti! and serving to prevent capacitance in the external circuit to the photocell from rendering the grid 83 sufficiently less negative to fire the tube ii The photocell anode I06 is connected by a Wire or conductor in! to the ground wire -51 via the wires 85, El! and 79. A resistor 38 is positioned in the Wire W! to block reverse current flow.

The operation of the system of Fig. 2 will be apparent from the operation of the system of Fig. 1, above described.

Having thus described the invention, what is desired to be secured by Letters Patent of the United States is:

1. In an electric controlling system, an electro tube having an anode, a cathode and a control grid, a circuit connected to said anode and said cathode, loading means in said circuit, a step-down transformer having its primary in parallel with said loading means, the transformer secondary having one end isolated from ground and having its other end connected to said grid, a condenser interposed between said transformer other end and said grid, a photocell,

a conductor connecting the photocell cathode to said grid, and a resistor in said conductor.

2. In an electric controlling system, an electron tube having an anode, a cathode and a control grid, a step-down transformer, a circuit connected to the primary or said transformer and to said anode and said cathode so that said primary is connected across the anode-cathode circuit, a conductor connecting one end of the transformer secondary to said grid so as to reverse the current flow to said grid relative to the current flow to said anode, a condenser in said conductor so that the maximum negative potential to said grid precedes the maximum potential to said anode, a condenser isolating the other end of said transformer from ground, a photocell, a conductor connecting the photocell cathode to said grid, a resistor in said last-named conductor, and a conductor connecting the photocell anode to ground.

FRED B. AUBERT.

REFERENCES (31TH!) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,650,092 Poulsen et a1. Nov. 22, 192? 1,938,742 Demarest Dec. 12, 1933 1,988,658 Kovalsky Jan. 22, 1935 2,849,647 Geficken et al. Aug. 4, 1936 2,140,350 Dawson Dec. 13, 1938 2,141,942 Suits Dec. 27, 1938 

